Cross-Staff stems not working

[Simon Bailey]

Hi,

consider this code:

\version "2.23.9"
\layout {
  \context {
    \PianoStaff
    \consists "Span_stem_engraver"
  }
}

{
  \new PianoStaff <<
    \new Staff {
      <ais' fis''>4 r r2 |
    }
    \new Staff {
      \clef bass
      \crossStaff { <dis dis'>4 } r r2 |
    }
  >>
}

What am I missing to get the stem to span the staves? I get the
attached output with two separate chords...

Thanks, kind regards,
sb

-- 
Do not meddle in the affairs of trombonists, for they are subtle and
quick to anger.

2022-06-25 13_57_52-Untitled [modified] – Frescobaldi.png
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